This invention relates to an air intake tube assembly for an internal combustion engine that includes an evaporative emission control device. More particularly, this invention relates to an air intake assembly wherein the evaporative emission control device comprises hydrocarbon vapor absorbing material protected by a rigid tubular body and inserted into the flow path through an elastomeric air tube.
In an automotive vehicle, a common system for supplying air to an internal combustion engine comprises an air intake tube, referred to as a zip tube, connected between an air cleaner canister and an air intake manifold of the internal combustion engine. There is concern over hydrocarbon vapors that may diffuse from the intake manifold through the tube when the engine is not running and may be emitted into the atmosphere. It has been proposed to include a material that absorbs hydrocarbon vapor in communication with the air flow path to absorb vapors diffusing from the intake manifold. The material is formed as a structure, such as a monolith, having gas passages to allow contact with the vapor-containing air. The material may be installed in a separate canister in the air induction system. However, this requires additional connections to the air induction system that add to the cost and the difficulty of assembling the air induction systems into the vehicle. Moreover, suitable vapor-absorbing materials, such as carbon or zeolite, are fragile and susceptible to damage due to incidental impact during handling and installation. Also, vibration during engine operation or vehicle travel over non-smooth road surfaces may result in damage during use. Such damage may dislodge particles that may restrict air flow to the engine or may be drawn into the intake manifold and potentially adversely affect engine operation.
Therefore, there is a need for an air intake tube for an internal combustion engine which includes an evaporative emission control device to absorb hydrocarbon vapors attempting to escape from the engine and may be readily installed with minimal connections, and further which protects the fragile hydrocarbon absorbing element from damage during installation and use.
In accordance with this invention, an air induction system of an automotive internal combustion engine comprises an evaporative emission control device inserted into an air intake tube that is connected to an air cleaner canister and an air intake manifold of the engine. The evaporative emission control device comprises a rigid tubular body that includes an upstream end and a downstream end. A hydrocarbon vapor absorbing element is disposed within the rigid tubular body. The hydrocarbon absorbing element comprises an upstream face that is recessed from the upstream end of the rigid tubular body and a downstream face that is recessed from the downstream end of the rigid tubular body. By recessing the faces of the hydrocarbon vapor absorbing element from the ends of the rigid tubular body, the rigid tubular body extends to protect the hydrocarbon absorbing element from incidental contact during installation and use. In addition, by forming the air intake tube of elastomeric material and inserting the evaporative emission control device therein, the air intake tube provides flexible support for the evaporative emission control device to protect against damage due to engine vibration or bumpy vehicle travel.